Soil sampling tools and devices are used for a variety of purposes, e.g., to obtain samples for soil moisture content or to sample a volatile organic compound (VOC) which may have permeated the soil. Sometimes a soil "coring" tool is used simply to explore for buried coins and the like. Examples of such tools are shown in U.S. Pat. Nos. 3,326,049 (Eley); 4,989,678 (Thompson) and 3,707,197 (Walesch et al.).
The device shown in the Eley patent has a barrel with air vent and a shaft threaded to the barrel. The shaft is graduated so that when turned, the soil sample is ejected in increments. The kit shown in the Thompson patent includes a sampling device and a sample containment device, both of which are used for analyzing a soil sample containing a VOC. The tool shown in the Walesch et al. patent is said to be useful for finding buried coins and the like. Other types of sampling tools and instruments are shown in U.S. Pat. Nos. 1,162,901 (Cantey) and 4,887,413 (Tuckey, Jr.).
It is common knowledge that tanks for storing liquids may, over time, develop a leak. If the tank is above ground, the leak is usually observed rather soon after its onset and not much damage results. On the other hand, there is an already-substantial and growing awareness that certain types of liquid storage tanks placed underground have a greater-than-normal propensity to deteriorate and leak. Such types include tanks made of common sheet steel from which protective coatings have either been eaten away or were non-existent. And a substantial factor contributing to the risk of tank leakage is that with an underground tank, leakage is not visible. Usually, such leakage can only be detected by excavation and testing.
And the risks are enormous. Undetected leaks of underground storage tanks can and do contaminate soil and potable water supplies, the latter by polluting underground aquifers from which a great deal of drinking water is drawn. Recent legislation recognizes risks presented by leaking underground storage tanks and provides for remediation of damage caused by such leaks. Because of the number of gasoline service stations and private fuel and solvent storage tanks, leakage of petroleum distillates and hydrocarbons is a particularly significant problem.
Good remediation requires that personnel be able to accurately determine the nature and extent of the leak. Such determination depends in large part upon the availability of high quality test instruments. The efforts of earlier workers in this regard have not been entirely satisfactory. For example, the Thompson patent emphasizes speed of transfer of a soil sample from a sampling tool to a containment device to minimize loss of VOC. This is clearly an impractical solution to retention of sample integrity, especially if the leaky tank was installed at a site distant from the analyst's laboratory. Earlier sampling tools fail to offer solutions reducing the substantial storage space required to transport dozens of tools to and from a site.
Establishing sample custody (through records relating a particular sample to a particular locale and, later, to a particular laboratory vial) is yet another aspect of good testing practice to which earlier tools have not been particularly responsive. An improved sampling tool which maintains sample integrity, which minimize required space and which helps establish a chain of custody would clearly be an important advance in the art.